This is how I make an ipod Line Out Dock (LOD)
This is not a definitive guide by any means. This will not work on all ipods. Some newer models than mine (3rd generation nano) need pins 15+16 left in and bridged with solder. And some need resistors soldered in. There are some realy good forums for this on Headfi.com if you need to do some research.
Now, LOD? This takes an audio signal out, bypassing the internal amplifier. And in this case, to an external headphone amplifier.
This one differs from most in that the cables exit from the left hand side and the connector body is made from scratch.
Some of the photos I took are not great and others were deleted from my phone - softwear error!
Hope this is useful.
Ipod glue together connector - from Quables
Mundorf gold 0.5mm / 24awg solid core wire - Online
24 awg OCC Solid core copper - Quables
Neutrik 3.5mm stereo Jack plug - online auction
Bootlace - both thick and thin.
PTFE Tape - plumers merchants
8mm OD brass tube - model shop
2x Brass pet address barrels - pet shop
Heat Shrink tube
2 part epoxy resin glue
Needle nosed pliers
Pin Vice plus drill bits
Stanley / craft knife
Wet and dry paper
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Step 1: Pulling Pins
For this LOD you only need pins 2, 3 and 4 on the ipod connector. This means that the other 27 need to be pulled out.
Pins are laid out as follows from left to right if looking at the connector from the front - the side that faces towards you as you look face on at the iPod:
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Pulling them ouy is easily done with a pair of needle nosed pliers. Take your time and make sure you get the right ones! These can be re inserted if needs be but it's far easier to leave them in.
Once these are out use a 'Dremel' with a cut off wheel to carefully cut away a portion of the connector closest to the pins. Then use side cutters to cut the pins down.
Step 2: Cables and Eye Strain...
Now you need to decide on the length of the cable.
Cut 3 strands of whatever cable you have chosen to the same length. I used Mundorf Gold for left and right and OCC copper for the earth.
Strip a small portion of the insulation at one end of all 3 wires - about 3 / 4mm and bend the end to a right angle.
Now it's time to solder. A fine cone tip is recommended for this if you have one. Tin the ends of the wires. Use a small paint brush to apply a little flux to all 3 of the pins. Now at this point I used a magnifying glass to solder the wires to the connector. If you have really good eyes then you might be ok, but be warned, these things are tiny!
Put the wire into position and hold the soldering iron onto it until the solder flows onto the pin. Repeat. There should be enough solder on the wire from tinning it.
Now is a good time to label your wires. I used red paint for right and blue for left - as is tradition. Beware, if you're using teflon coated cables this will soon wear off. More on that later.
This is also a good time to test continuity of the wires using a multi meter, if you have one. This is to ensure you haven't shorted anything out. If you don't have one, as I don't, then it's time to pray your soldering is good and that you're not about to waste your time and money.
Step 3: Cable Strain Relief
Cut a short length of toothpick / plastic rod / cable insulation - Anything that is non conductive. Use super glue to stick this onto the connector, seperating pin 2 from 3 and 4.
Mix up some 2 part epoxy resin- I use the 2 minute setting type for most stuff as im quite impatient.
Apply liberally over the soldered wires and the piece of chosen pin seperating material until all are encapsulated.
Don't go too mad with this and try not to go onto the front or back of the connector.
Leave to set.
Step 4: Making the Body
Roughly mark the brass tube to the required length using a permanent black marker pen. In my case this was around 28mm. Carefully scribe an accurate line all the way around.
Hold this in the bench vice and cut through a small section of the tube. Rotate the tube and make another cut. Repeat untill this is cut all the way around. Making small cuts all the way around prevents the blade from binding up, gives a more accurate cut and is easier.
File the rough end till it is smooth and square.
Apply more marker pen along the length of the tube. Measure the width of the connector at the widest point - 4.5 / 5 mm. Scribe 2 lines along the tube at just under this distance appart,
Gently hold in the bench vice and cut about a quarter of the way along one of the lines. Swap to the other line and cut. Slowly saw along each line, swapping from one to the other, in order to maintain some strength and structual integrity to the tube.
When the slot is cut file along the cut edge till it is smooth and the connector will slide in from one end. You want a good fit, not too loose or tight.
Take the 2 pet address barrels and unscrew the bottom half of each. These are the bits you need. Use a 'Dremel' with a small grinding bit to grind a semi circle into the side of each of these. Try to get this the same width as the slot you cut in the tube.
Take one and drill a hole in the end. I used a pin vice and 2.5mm drill bit to do this slowly by hand as the barrel end is quite small and delicate. If you drill from the inside there should be a depresion in the centre from manufacturing, so you shouldn't need to centre punch the hole first. Use your grinding tool to enlarge the hole to the required diameter. File and sand this smooth, then polish.
Step 5: Pre Assembley
Time to sleeve the cables. For this LOD I used fine boot lace (for the last one I used Insulation stripped from some spare flex).
Cut the ends of the boot lace and strip out the central core. This leaves you with a hollow cloth tube. Cut 3 pieces slightly shorter than your wires and slide these over. Secure these at either end with a small blob of copydex glue.
Now back to painted teflon wires. By this stage almost all the red and blue paint will have rubbed off off the right and left wire. Re-apply paint onto the boot lace before it's gone completely.
Carefully cut some 1mm thick sheet styrene to about 5mm X 24mm - X2 using a stanley / craft knife and a metal ruler. Bevel the top and bottom of both of these.Glue one of these to each side of the connector using super glue.
You may need to do more filing / sanding to ensure that the connector - complete with added side pieces - slides comfortably into the brass tube.
Once you're happy with the fit try the end pieces out.
Now wrap all 3 bootlaced cables together with PTFE tape. Try and do this as neatly and evenly as possible or it will look terrible later on. I used about 5 layers on this one. Now use some wider diameter, hollowed boot lace to sleeve the whole thing. Stop at the same point as you did with the PTFE tape. Secure the ends with copydex.
Step 6: Final Assembly - Sort Of...
Now it's time to glue all this stuff together. I mixed up some 2 part epoxy resin and filled the gap between the two styrene side pieces on the underside of the connector. Put a little on either side of the styrene plates too.
Now slide this into the tube. Keep a cloth / rag / tissue handy to wipe off any excess as you go. Fill the end opposite to the cables with glue and make sure you have the connector centered. Now push on the brass pet address barrel so that the ground out portion fits around the connector.
Do the same with the other barrel. You need to work quite quickly before the glue goes off and make sure you wipe off any overspill - it's much easier to do it now rather than trying to get it off later.
Leave this to set. Once it's done you need to thread the jack plug body onto the cable followed by a piece of heat shrink tube.
Now its time to solder...
Step 7: Soldering!
It's time to finish this thing off!
This is not as complete as I had intended as the majority of photos that got lost were from this section of the build.
Slightly bend out the wires and strip about 4mm of insulation from the ends. Thread these into the appropriate holes on the headphone jack plug. This can be quite tricky. I usualy get the earth and right lead bent into position and thread these in. Then use some tweezers or needle nosed pliers to bend the left lead and thread it into the hole.
Ensure that the cables are sitting inside of the (currently) open strain relief clamp at the bottom of the jack.
Solder these up.
Now its the moment of truth... Before you shrink tube this its time to test it. Audio joy! Or crushing disappointment? This one worked and it sounds really good.
Carefully crimp the strain releif around the cables with a pair of needle nosed pliers. Slide the shrink tube over the connections on the jack and shrink it.
Slide the jack body up and screw it onto the jack plug.
Step 8: Sit Back and Enjoy!
Now you're done it is time to 'burn in' those cables!
You may notice that the jack plug ended up covered in heat shrink tube. There are 2 reasons for this. One is that I wanted the additional strain releif, which is why I continued for about 10mm on to the cable.
Reason number two is that I thought this would be 'gold' plated copper like the other one I used. Sadly it wasnt. It looked so hideously cheap that something had to be done.
There are a lot of forums online about different types of cable and its relative audio merits. If you're interested check out headfi.com for some opinions.
I have so far tried OFC Copper, Stranded silver, solid core silver, silver plated copper and solid core silver + gold alloy / copper hybrid and all have different sound qualities to my ears.
Now sit back and enjoy the melodies!